エラトステネスの篩
DIM a(1000)
FOR b=2 TO 1000
LET a(b)=b
NEXT B
REM------------------------------------
FOR i=2 TO 1000
FOR j=2 TO 1000
IF i<>a(j) AND MOD(a(j),i)=0 THEN LET a(j)=0
NEXT J
NEXT I
REM ------------------------------
LET t=1
FOR k=2 TO 1000
IF a(k)<>0 THEN PRINT t;"番目の素数" ;a(k)
IF a(k)<>0 THEN LET t=t+1
NEXT K
END